Struggling to understand Adding Numbers to Multiples

[user1622]

Hi

I have been doing the overwhelmed plan and I am struggling to understand the “Adding Numbers to Multiples” (Home - GregMat - GregMat)

I havent really understood the concept. Can someone please dumb it down more than what Greg does because I have watched the videos three times now and tried attempting the quiz and havent really been able to answer any of the questions each time that I have tried to do so.

I’m open to try another source to understand it as well if someone used it during their preparation

[ganesh]

Hi, I think the basic TLDR rule is:

When you add 2 integers together, the sum will have all the factors they have in common, but also something new.

Here, 10+25 both share a 5, so 25 has that but it also has an extra 5

Or in this example:

We can see there’s an extra 2 in 72. Which means it’s now divisible by 8 and 24, which the two 36s weren’t.

[user1622]

Understood. Thank you!